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Ioannis K. Chatjigeorgiou

Séminaire irrégulier

School of Naval Architecture and Marine Engineering, National Technical University of Athens

Continuum systems like straight bars subjected to parametric excitation, namely, to forced dynamic sinusoidal loading inline with the structure's axis of symmetry, experience under specific conditions the so called buckling phenomenon that could lead to Mathieu type instabilities.

In the case of riser type catenary shaped slender structures, it has been determined that the application of fast heaving motions at the top terminal point may lead to compression loading. This effect is reflected as an extreme increase of the total bending moment at the touch down region. Heaving motions are extremely influential when the catenary has a nearly vertical configuration and thus, the imposed heaving motions can be considered with sufficient accuracy as an axially imposed loading.

Are these previously mentioned phenomena, somehow connected ?

This lecture presents the details of a relevant investigation that explores the cause of the dynamic bending moment amplification by employing efficient methods of nonlinear dynamics.